My homeworld has 100% development, +5% for the presence of gold(Human race), +30% for the presence of a Wonder(tested with multiple wonders, happens with any of them). So a total of 135%.

With just the above list of modifiers I can still edit the planet. I can build additional wonders and it does not change the development rating or cause issues. However, the moment I get one of the rare resources such as Zentabia Fluid or Korabbian Spice(and their resulting +30% to planet development) I receive an error when I try to edit the planet. JIT error text is:

If I lose access to the rare resources and wait for the stockpiles to drain off my planet, the development rating drops back down to 135% and I can once again access the planet in the editor.

This only seems to happen if I have both a Wonder/ruin and the rare resource. One or the other and there are no issues. I'm not sure if the problem is a result of 165% simply being too large of a value for the editor to handle.

I can pretty much re-produce this at will, so please let me know if there is anything else you need.

Edit: I played around with removing all my wonders then adding a ruin that I could slowly tweak up the bonus rating on. It looks like the magic number is 160%. After that the editor barfs.

This still appears to be happening with 1.7.0.15. Wekkarus planets with an Underwater Palace and access to one of the rare resources can have 190% development. Attempting to use the editor on such a planet returns the following error: